Protectors



Oct. 3, 1961 s. M. KLINE 3,

PROTECTORS Filed Feb. 4, 1959 INVENTOR. SSCIKJELL (0'). KL! Er Filed Feb. 4, 1959, Ser. No. 791,216 1 Claim. (Cl. 215-12) This invention relates generally toprotectors for fragile articles and more particularly to a film of foamed plastic for protecting fragile articles.

A common practice in the packaging of fragile articles such as Mason canning jars, laboratory glassware, glass bottles, etc., in cartons is to place interlayers or partitions between the articles so that no two articles will contact with each other and so that the interlayers will absorb any shock and vibration resulting from the handling and transporting of the carton. Usually these interlayers are of corrugated cardboard or chipboard.

Protecting fragile articles in the manner mentioned above has a number of disadvantages. The corrugated cardboard or chipboard must be cut, as with slots to per-- mit interlocking of the interlayers at each place where they intersect each other in the carton. When the size of the articles to be packaged is not uniform, these slots are required to be positioned differently, and the carton manufacturer must have available a variety of dies which can be changed on the presses to cut the slots at different positions. Furthermore, the carton must be large enough to accommodate both the articles and the interlayers and the additional weight and size of the carton and interlayers are factors in the cost of packaging and ship- P 8- Foamed plastic material is well-known. For example Carl Georg Munters and John Gudbrand T andberg described in Patent No. 2,023,204 the production of foamed polystyrene for use as insulation. It has been proposed heretofore to use foamed plastic to protect articles from shock and vibration. However, efforts heretofore have been to encase the article in the foamed plastic by either foaming the palstic in situ around the article or by foaming the plastic about an article having a shape identical to the article to be protected and slitting or otherwise providing for the casing to be slipped about the article. This has been troublesome and expensive.

It has now been found in accordance with this invention that fragile articles may be protected by surrounding the article with a film of foamed polystyrene even though the film be as thin as 0.02 inch in thickness.

Advantageously used for this invention is a film of foamed polystyrene having an average cell size of 0.004 inch, an average cell wall thickness of less than 0.0004 inch, and a density of 0.75 to 8 pounds per cubic foot. Such film may conveniently be prepared by a process such as described in application Serial No. 780,934, filed December 17, 1958, by Albert R. Kudlach and assigned to the assignee of this invention. The foregoing application describes the production of foam through the use of conventional extrusion apparatus by extruding, at a cylinder temperature of ISO-260 F. and a die temperature of 250-290 F., polystyrene particles which have integrated therein from about 4 to 9 percent of an aliphatic hydrocarbon boiling approximately in the range of 30- 90 C. and which have homogeneously admixed therewith a carbon dioxide liberating agent and an acid in an amount sufficient to produce upon reaction a total of about percent by weight of water and carbon dioxide based on the weight of the polystyrene particles.

The above and further novel features of the invention will appear more fully from the following detailed description when the same is read in the light of the accompanying drawing. It is to be expressly understood,

ted States Patent 0 Patented Oct. 3;, 1961 however, that the drawing is not intended to be a definition of the invention but is for illustration only.

The single sheet of drawing illustrates an embodiment of theiuvention being used for the protection of a bottle.

Referring now to the drawing, a sleeve 1 of foam polystyrene is being placed on a bottle 2 to protect the bottle during handling. This sleeve may be cut to length before having the bottle inserted therein or the sleeve may be a portion of a roll of film which has the free end placed over the article and the film cut to the desired length. Conventionally, film is extruded as a cylinder, and although the sleeve 1 is cylindrical in shape and the bottle is rectangular in shape, the sleeve substantially conforms to the shape of thebottle in so far as the outer perimeter of the bottleand the inner perimeter of the sleeve are substantially the same. The thickness of the sleeve is a practical matter, although it has been found that a sleeve having a thickness as little as .02 inch is suflicient to protect most fragile articles from the shock due to conventional handling.

The sleeve 1, as stated before, may be made by the process described in the aforesaid application Serial No. 780,934 although other conventional processes may be used. In forming sleeve 1 by the process of application Serial No. 780,934, for example, there was used polystyrene particles having integrated therein 7 percent petroleum ether boiling approximately in the range of from 30-90 C. and having homogeneously admixed therewith 0.5 percent by weight of the polystyrene of sodium bicarbonate and 0.4 percent by weight of the polystyrene of citric acid. These polystyrene particles were fed into the hopper of a National Rubber Corporation extruder. A 2:1 compression ratio constant taper smooth torpedo screw was used, a temperature of 220-240 F. was maintained in the cylinder while a temperature of 240 F. was maintained in the die, the screw speed was set at 50 rpm, the blow up ratio 4:1, the pull down ratio 05:1 and a take off speed of 28 feet per minute. The film of foamed polystyrene so produced had a thickness which varied from 0.03 inch to 0.04 inch, had a density of 6 pounds per cubic foot, an average cell size of 0.0014 inch, and an average cell wall thickness of 0.0002 inch.

When the sleeves are produced by an extrusion process, the sleeves may be extruded so as to have an inside diameter slightly larger than the external perimeter of the particular articles to be protected. The tubing so produced may he slipped over the article to protect the article against shock due to handling. The sleeves may be cut to length before or after being placed on the article that is to be protected.

To provide for a snug fit of the sleeve on the article, the sleeve may be made slightly smaller than the article and then stretched over the article. This is possible since a typical film of extruded foam polystyrene has an elongation of between 8 and 12 percent. When the sleeve is smaller than the article, air may be injected into one end of the length of the sleeve, whereby the air serves as a lubricant, as the other end of the sleeve is slipped over the article, or a mechanical spreader having fingers which will grip the leading edge of the tubing may be used to slip the sleeve over the article.

A snug fit may also be made by sliding over the article a sleeve whose inner perimeter is substantially the same size as the article, thereafter subjecting the sleeve to radiant heat whereupon the film of foam polystyrene expands further in thickness and engages the article.

While the drawing illustrates the sleeve 1 as being substantially the size of the bottle, it will be recognized that the sleeve may have a length less than the length of the article and that several sleeves may be placed at spaced positions along the article to be protected. It will also be recognized that these sleeves may have prin ed matter thereon so as to serve as labels for the article as well as protectors. It is also to be recognized that the term fragile article, includes not only glassware but other fragile articles, such as eggs. to be regonized that the film of foamed polystyrene may be wrapped about the article as well as' being slipped over the article.

The foregoing has described the protection of fragile articles from breakage during normal handling by'surrounding the article with a film of foamed polystyrene. The foamed plastic film may be extruded as a film, flattened to a sheet, placed on a roll and used as needed, cutting the sleeves to the desired length for the article. 'Due to the thinness of the film of foamed plastic and its low density, such protectors provide great savings in the weight and bulk of the packaged article.

What is claimed:

A method of protecting siliceous fragile articles from shock and vibration during the handling thereof, which- It is also present in an amount sufiicient to produce upon reaction a total of about 5 percent per weight of water and carbon dioxide based on the weight of polystyrene particles to produce a film of at least 0.02 inch in thickness of foamed polystyrene, forming said film into a sleeve, the inner-cross dimension of the sleeve being only slightly greater than. the external cross dimension of the article to be protected, whereby said sleeve is readily removable from said article without deforming said article or destroying said sleeve, and surrounding said article with the removable sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 739,514 Street Sept. 22, 1903 2,722,719 Altstadter Nov. 8, 1955 2,836,319 Pinsky et. al. May 27, 1958 2,929,525 Glover etal. Mar. 22, 1960 FOREIGN PATENTS 834,507 Germany Mar. 20, 1952 OTHER REFERENCES Modern Plastics, 83-86, 166, 167, October 1950. 

